This invention relates to the field of mechanical hand controllers. More particularly, in preferred embodiments the invention relates to a haptic device that provides sensory feed-back to a user, to a preferred form of rotary electrical actuation or xe2x80x9ctorquerxe2x80x9d for activating the controller, and to a user input system suited to haptic controllers.
Hand controllers are known wherein a handle is carried at the outer end of an arm extending from a five-bar linkage. In known arrangements, two of the rotary joints of the five-bar linkage are both equipped with rotary sensors and rotary actuators. A control processor receives signals from the sensors that correspond to the position of a cursor point located at the distal end of the arm in the X-Y plane. The handle, which may be of pen-like form, is used to move the distal end of the arm with its cursor point. Signals from the sensors are processed to move a video cursor on the screen of a video terminal in correspondence with the X-Y location of the cursor point within the working space of the controller.
With actuators present, the control processor is able to apply forces to the handle in correspondence with the movement of the cursor point and/or in relation with images present on the video terminal screen, providing haptic feed-back to a user. For example, in computer-aided drafting, a xe2x80x9cCADxe2x80x9d system, the presence of a line on the screen can be haptically signalled to a user by a resistance to movement of the cursor point that would cause the video cursor to otherwise move across a line present on the video screen.
In the prior art system disclosed above, no provision is made for input to be provided in response to movement of the handle in the Z direction. No provision is made for the arm to be actuated in the Z direction or otherwise function in response to motion in the Z direction. One object of the present invention is, therefore, to provide an arrangement whereby movement of the cursor point in the Z direction may be exploited to provide additional functionalities, signal input to the control processor and, optionally, haptic feed-back.
In the prior art system referenced, a pressure sensitive tip on a stylus-format handle carried at the end of the arm supported by the planar five-bar link was able to provide signals to the control processor when pressed on to a tablet. These pressure responsive signals were used to mostly replace the function of a button. No provision was made, however to use such signals to control the character of the haptic stimulus generated by the hand controller. Further, no information as to the position of the stylus in the Z direction (other than contact of the tip with a tablet) was combined with the output from the pressure sensitive tip to affect the operation of the hand controller. The present invention addresses these omissions to provide improved functionality in a hand controller.
In actuating a haptic controller based on rotary devices that control rotary joints in a five-bar linkage, it has been felt necessary in the past to use discrete electromagnetic torquing devices. These devices, called -xe2x80x9ctorquersxe2x80x9d-, have operated on the basis of the Lorentz effect wherein a moving coil positioned within a magnetic field tends to or exert a torque or a force, that depends on the current passing through the coil. When multiple, discrete torquers are employed, the parts of the respective torquers are duplicated in each other. An object of this invention is to provide a torquing device wherein two or more torquing arms share commons structural aspects, thus reducing the total parts needed in providing two rotary actuators.
The invention in its general form will first be described, and then its implementation in terms of specific embodiments will be detailed with reference to the drawings following hereafter. These embodiments are intended to demonstrate the principle of the invention, and the manner of its implementation. The invention in its broadest and more specific forms will then be further described, and defined, in each of the individual claims which conclude this Specification.
According to one aspect of the invention, a hand controller incorporates a sensing arm assembly for a position sensing mechanism comprising:
(a) an arm having a moveable operative end and a mounted end carried by a fixed base;
(b) support means coupled between the mounted end of the arm and the base, said support means providing the arm with two degrees of freedom in horizontal directions about the base and one rotational degree of freedom about an arm rotational axis located at the mounted end of the arm, said arm rotational axis permitting the operational end of the arm to be displaced vertically with respect to the horizontal plane;
(c) horizontal position sensing means carried by the base to sense the location of the operative end of the arm in horizontal directions;
(d) vertical displacement sensing means carried by the base, and preferably positioned at the mounted end of the arm, to sense the vertical displacement of the operative end of the arm with respect to the mounted end;
(e) output means coupled to the horizontal position sensing means and to the vertical displacement sensing means to provide output signals from such sensing means
whereby the output signals correspond to the location of the operative end of the arm in three dimensional space.
Such a sensing arm assembly is suited for use in an hand controller having a handle mounted at the operative end of the arm for movement of such end, and a cursor point located therein, through space.
The invention in an alternate description is directed to a hand controller comprising:
(a) a base;
(b) a grasping handle free for movement about a horizontal plane;
(c) a linkage positioned between the base and the handle having base and distal ends;
(d) horizontal position sensors carried by the base to provide signals corresponding with the position of the grasping handle with respect to the horizontal plane; and
(e) an arm extending between the handle and the distal end of the linkage, characterized by:
(i) hinge means carried by the linkage permitting the arm to be displaced upwardly and downwardly with respect to the horizontal plane; and
(ii) vertical displacement sensing means carried by the linkage for sensing the vertical displacement of the grasping handle.
Again this hand controller may include biasing means connected between the linkage and the arm for returning the grasping handle to a zero position in respect of vertical displacements in at least one vertical direction. This biasing means may provide a restoring force directing the handle towards the zero position wherein the restoring force varies linearly or functionally the displacement of the handle end from the zero position.
The zero position for the cursor point may be located in a plane that is elevated above the surface over which the cursor point may move, thereby providing a xe2x80x9cvirtual tabletxe2x80x9d surface; or it may cause the operative end of the arm to become automatically parked against an actual tablet surface.
In effect the arm of the invention has one rotational degree of freedom about an arm rotational axis located at the base end of the arm, this arm rotational axis preferably lying substantially in the horizontal plane. This axis permits the operational end of the arm to be displaced vertically with respect to the mounted end. To this combination may be added vertical displacement sensing means positioned at the mounted end of the arm to sense the vertical displacement of the operative end of the arm whereby a signal corresponding to the location of the operative end of the arm in the vertical direction is provided.
As a convenient means of providing the restoring force, the sensing arm may be equipped at its mounted end with an elastically bendable protrusion coupled at its root end to the arm, functioning as an elastic hinge. This protrusion has a protruding, free end that is constrained against vertical displacement in at least one vertical direction by a seat carried indirectly by the base through the intervening linkages. This is one example of a biasing means for positioning the arm. Other known biasing means, such as those using coil or leaf springs, may also be employed.
The mounted end of the arm may also include a position sensor that relies on a reflecting surface present on the arm. This surface, which is displaced with the arm, serves as part of the vertical displacement sensing means. A light detector is positioned to sense the vertical movement of the operative end of the arm by the reflection of light off of the reflecting surface as it moves with the mounted end of the arm. As the reflecting surface rotates with the arm, the light detector is able to sense the rotation of the arm by the amount of reflected light that it receives off of the reflecting surface. This is one example of a position sensor for the arm. Other known sensor arrangements, such as those using rotating potentiometers, may also be employed.
As a preferred means of incorporating the sensing arm assembly into a hand controller, a five-bar linkage having a base end with a base link, a distal end with two distal links separated from the base end by two intermediate, proximal links, may be employed as a support means for the arm. This linkage extends from the base and is connected to the mounted end of the arm through one of the distal links of the five-bar linkage. In this arrangement the horizontal position sensing means may be located astride the five-bar linkage and the base, sensing the orientation of the proximal links and thereby the position of the distal links and the operative end of the arm in the X, Y directions.
More specifically, the horizontal position sensing means may be in the form of two rotational sensors carried by the base and respectively connected to a proximal link, the rotational sensors each having a common, shared, axis of rotation, ie. their axes substantially coincide with each other. These rotational sensors may conveniently be constructed in a compact form combined with actuators as next described below.
As a further feature of the invention, the arm assembly may include not only horizontal position sensors but also linkage actuators whereby the operative end of the arm may apply forces in horizontal directions, with arbitrary direction and intensity, to the handle. A similar actuator arrangement may actuate the handle in the vertical direction.
A preferred form of torquing actuator capable of applying two or more independent torquing forces to a corresponding number of linkages in the assembly may comprise:
(1) a frame having a central axis;
(2) one or more magnetic circuits formed by corresponding one or more magnets carried by the frame and positioned to provide in an adjacent air gap a plurality of spatially separated, reversing, magnetic field regions;
(3) two or more electrical coils respectively coupled to output links, the coils being supported-within the frame for rotation about the central axis and each being positioned within the air gap to intercept the one or more magnetic circuits respectively across one of the reversing magnetic field regions; and
(4) electrical coil activation means for supplying current to said multiple coils,
whereby, upon activation of said coils, the output links may be caused to be independently activated. By positioning the respective coils in a shared or overlapping air gap, mounted for rotation on trajectories which would collide or intersect if extended, a highly compact arrangement for providing a multiple torquer assembly may be constructed.
Further features of the invention include the presence on the handle, preferably on a handle of pen-like format, of one or more switches and/or electrical sensors that may be actuated by the users. These switches may provide off-on signals to a central control processor. employment of a grip pressure sensor will provide a varying output dependent upon finger pressure.
Such grip pressure sensors may operate to provide a variety of functional consequences when included as part of a haptic hand controller system. As a preferred feature, pressure applied to such a sensor may be used to control the intensity or level of detail with which haptic feedback is provided to the user in proportion to the degree of pressure applied to the handle. Alternately, or cumulatively, the pressure signal from the handle may be combined with the position of the handle with respect to the vertical or xe2x80x9cZxe2x80x9d axis to cause the control processor to vary the presence or absence of haptic feedback in conjunction with the position of a video cursor on a video display screen. Both off-on and pressure signals from this handle may be combined with position signals from the arm position sensor to provide multiple levels or xe2x80x9cplaying fieldsxe2x80x9d in which the haptic behaviour of the system differs.
The foregoing summarizes the principal features of the invention and some of its optional aspects. The invention may be further understood by the description of the preferred embodiments, in conjunction with the drawings, which now follow.